Ethiopian Prime Minister Meles Zenawi has died aged 57 in a hospital abroad, the government says.

It did not give details but an EU spokesman later told journalists Mr Meles had died in Brussels, Belgium.

Mr Meles had not been seen in public for weeks and speculation about his health mounted when he missed a summit in Addis Ababa last month.

His deputy, Hailemariam Desalegn, becomes prime minister until elections due in 2015, state media reported.

Mr Meles took power as the leader of rebels that ousted communist leader Mengistu Haile Mariam in 1991.

He is credited with spearheading economic development in Ethiopia - but, critics charge, at the price of respect for human rights.

Analysis

By James CopnallBBC News

Meles Zenawi's death will have repercussions far beyond his country.

He was undeniably central to everything in Ethiopia - the good and the bad, the economic growth and development, as well as the repressive climate denounced by opposition politicians and journalists.

But he also played a key role in the region.

Since Mr Meles took power in 1991, Ethiopia has seen Eritrea secede, then fought a war with the new country. It also twice sent troops into Somalia to fight militants linked to al-Qaeda.

Ethiopia also has peacekeepers in Abyei, the border region claimed by both Sudan and South Sudan.

Political leaders in all these countries will be carrying out rapid calculations about what Mr Meles' death means for them.

The West has also lost a key ally in the Horn of Africa.

Now the attention will switch to whether Mr Meles built a strong enough system to outlast him.

He was austere and hardworking, with a discipline forged from years spent in the guerrilla movement - and almost never smiled, says Elizabeth Blunt, the BBC's former correspondent in Addis Ababa.

Liberian President Ellen Johnson Sirleaf said Mr Meles was an "intellectual leader for the continent", and UK Prime Minister David Cameron called him "an inspirational spokesman for Africa" who had lifted millions out of poverty.

But a spokesman for al-Shabab Islamist militants in Somalia - where Mr Meles twice sent troops to fight - told Reuters news agency they were "very glad" of his death, saying Ethiopia was "sure to collapse".

Ethiopia's Council of Ministers announced "with great sadness the untimely death of Prime Minister Meles Zenawi" in a statement, state TV reported.

The statement said Mr Meles had been receiving medical treatment abroad for the past two months and that his health was improving. But he developed a "sudden infection" on Sunday and despite emergency treatment, died at 23:40 on Monday.

European Commission spokesman Olivier Bailly later told a regular news briefing that Mr Meles "passed away during the night here in Brussels".

It's a very, very sad day for the people of the Republic of South Sudan and the people of the East African region as a wholeBarnaba Benjamin, South Sudanese Information Minister

A period of mourning had been declared until the funeral, for which no date has been announced.

State television said his body would be flown to Addis Ababa later on Tuesday.

Instability concerns

Mr Hailemariam, who is also Ethiopia's foreign minister, will become acting prime minister, government spokesman Bereket Simon told reporters.

He said an election was not necessary as the "constructional procedure" allowed for Mr Hailemariam to "kick off as a full-fledged prime minister".

In an earlier news conference, Mr Bereket said Mr Meles had struggled with illness for a year, but he had continued to work regardless.

Media playback is unsupported on your device

Media captionLiberian President Ellen Johnson Sirleaf: "He stood out because of his intellect...He will be missed"

Concerns have been expressed - including by Kenyan Prime Minister Raila Odinga - that Mr Meles's death could lead to a power vacuum and dangerous instability in Ethiopia.

But Mr Bereket insisted the country was stable and that "everything will continue as charted" by the late prime minister.

This theme was echoed by state television, which stated that "even if Ethiopia has been badly affected for missing its great leader, Prime Minister Meles Zenawi initiated fundamental policies and strategies which will be further strengthened".

Ethiopia's economy has grown rapidly in recent years, despite the secession of Eritrea and the subsequent war between the two countries.

Meles Zenawi

Emerged from Tigray People's Liberation Front (TPLF), which carried out armed struggle against Communist military regime in 1970s and 1980s

Became president in a transitional government in 1991 and then prime minister in 1995

Married another TPLF veteran, Azeb Mesfin, and had three children

Under his leadership, a closed and secretive country gradually opened to the outside world

But reputation tarnished in 2000s amid increasing repression in Ethiopia